Orchids can actually live healthy without fertilizers, if you provide them with proper care, which means sufficient watering, exposing it to enough light and pruning it when needed. Since orchids need less fertilizer than any other plants, the use of a fertilizer should be applied with caution by always using a well-diluted fertilizer mixture. Over-fertilizing can harm or even kill an orchid.
Three major chemical components of a fertilizer are nitrogen (N), phosphorous (P) and potassium (K= Kalium). Those three components are usually labeled as N-P-K and printed as numbers on a commercial fertilizer label. These numbers represent the percentage of each component. A labeling of 20-20-20 for instance, means that it contains an equal content of 20% each. Other elements that are needed by a plant are calcium, magnesium and sulfur, which can be found in lesser amounts.
As there are many commercial fertilizers with various compositions, you may as well make your own orchid fertilizer using some unused kitchen items that may contain N-P-K like eggshells, chicken bones, rice water, tea bags and milk.
Eggshells are viable sources of calcium and potassium and can be used as fertilizer. Don’t throw away eggshells, wash and collect them until you get 20 – 25 eggshells. Crush them with a mortar and then boil them in a gallon of water. Let them soak for 8 hours and then filter out the eggshells and keep the water in a container. You can use it to water your orchids on a weekly basis.
Dried and crushed chicken bones are another kitchen waste that is useful as a calcium and potassium source. Again, do not throw away chicken bones, but wash them and spread them out in the sun to dry or dry them in an oven. Crush the dried bones thoroughly and keep them in a jar. Sprinkle the dusty bones onto the potting medium on a monthly basis.
Rice water is a good source of vitamin, vitamin B in particular. This is the water that is used to wash the rice prior to cooking as well as the water in which the rice is cooked. You can directly use it to water your orchid. But make sure that you cool down the cooked water first.
Tea contains non-toxic organic materials and is rich in nitrogen which is good for orchids. Hence you can make use of teabags. Just open the teabag and pour the tea onto the potting media once a month.
Milk can be a source of protein, thus providing a high content of nitrogen. You can make use of a milk bottle or carton which has just been emptied. Fill it with water and shake it well so that the milk residue will be diluted in the water. Use this to water your orchid.
Fallen oak leaves are naturally a good source for fertilizer. And since they are completely natural, there is no need to worry about the negative effects of chemical fertilizers. Collect dry leaves and put them in a 5 gallon container then fill it with about 2 gallons of water. The portion should be 1/3 water and 2/3 of the leaves. Expose it to sunshine for about a week or until the water shows an ice-tea color. If you couldn’t get the ice-tea color after a week, add in warm water and let it cool down. You can then use it to water your orchid on once every 2-week basis.
Potatoes are another practical source of calcium and potassium. Cut an unpeeled potato into small dices and let it boil for a few minutes. To provide more potassium, you can add fresh banana slices into the boiling potato mixture and stir it well. Let it cool down and keep the mixture in jar. Add this mixture to the potting media once every 2-week basis.
Last but not least is molasses which acts as source of potassium. Just take a teaspoon of molasses to be diluted in the water you are going to use for watering your orchid. Epsom salt is also a good source of magnesium.